/*这是一个多进程的并发服务器,每来一个新的客户端就会分出一个子进程来处理收发*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 30
void error_handling(char *message);
void read_childproc(int sig);

int main(int argc, char **argv)
{
    int serv_sock, clnt_sock;
    sockaddr_in serv_adr, clnt_adr;
    pid_t pid;
    struct sigaction act;
    socklen_t adr_sz;
    int str_len, state;
    char buf[BUF_SIZE];
    if (argc != 2)
    {
        printf("Ussage : %s <port>\n", argv[0]);
        exit(-1);
    }
    act.sa_handler = read_childproc;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    state = sigaction(SIGCHLD, &act, 0);
    serv_sock = socket(AF_INET, SOCK_STREAM, 0);
    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_adr.sin_port = htons(atoi(argv[1]));
    bind(serv_sock, (sockaddr *)&serv_adr, sizeof(serv_adr));
    listen(serv_sock, 5);
    while (1)
    {
        adr_sz = sizeof(clnt_adr);
        clnt_sock = accept(serv_sock, (struct sockaddr *)&clnt_adr, &adr_sz);
        if (clnt_sock == -1)
        {
            continue;
        }
        else
        {
            puts("新的客户端到来了。。。");
        }
        pid = fork();
        if (pid == -1)
        {
            close(clnt_sock);
            continue;
        }
        else if (pid == 0)
        {
            close(serv_sock);
            while ((str_len = read(clnt_sock, buf, BUF_SIZE)) != 0)
            {
                write(clnt_sock, buf, str_len);
            }
            close(clnt_sock);
            puts("client disconnected...");
            return 0;
        }
        else
        {
            close(clnt_sock);
        }
    }
    close(serv_sock);
    return 0;
}

void read_childproc(int sig)
{
    pid_t pid;
    int status;
    pid = waitpid(-1, &status, WNOHANG);
    printf("子进程已经移除：%d，返回值是：%d\n", pid, WEXITSTATUS(status));
}